The parent companies of the two airlines, AMR Corp. and US Airways Group, have formally become American Airlines Group Inc., with common shares traded on Nasdaq under the symbol AAL. The new airline will be based in Fort Worth, Texas.

Officials for the airlines say it may take up to two years before the employees and planes for the two carriers operate as one.

For now, the two airlines operate separate websites and reservation systems. By early January, passengers are to be able to earn and redeem miles when traveling on either carrier, as well as reciprocal American Admirals Club and US Airways Club benefits and reciprocal elite recognition.

Together, the two airlines are to operate nearly 6,700 daily flights to more than 330 destinations in more than 50 countries and employ more than 100,000 workers.

The merger has the support of several labor groups, including the Assn. of Professional Flight Attendants for American Airlines, which faced an uncertain future after AMR Corp. filed for bankruptcy in 2011.

“Christmas has come early for the APFA,” said union President Laura Glading. “It’s been a long, tough slog, but today our hard work has paid off.”

If demand for air travel continues rising at its current pace, many of the nation’s biggest airports — including Los Angeles International Airport — will face holiday-like congestion once or twice a week within the next decade.

In a speech that stirred political controversy in two countries, Israeli Prime Minister Benjamin Netanyahu told Congress on Tuesday that negotiations underway between Iran and the United States would "all but guarantee" that Tehran gets nuclear weapons to the detriment of the entire world.